UK friend (well experienced in the business in the UK) opened a restaurant in Pattaya. What he hadn't anticipated was the high level of skimming of receipts, theft of food/raw materials and theft of finished meals not ordered but prepared and put aside (hidden) for staff to take home, not paid for.
Also theft of furniture and equipment. Tally up the bills presented to customer compared to cash in hand every shift/day. Always up to 50% short.
He tried to implement a rule that he alone checked bills before bill goes to customer, he alone takes the money, money locked in a drawer, he alone has keys. Staff rebelled with '...you not nice you don't trust your staff, don't want to work in place like this, no fun'.
He discovered that he couldn't take a day off/go home early, if he did theft increased substantially. Also discovered that asking questions was a waste of time, no answers whatever.